T1 and E1 are interfaces for telecommunications channels. T1 comprises the North American format for digital transmission of data. T1 supports data rates of 1.554 Mbits per second. A T1 line comprises 24 individual channels, each supporting 64 Kbits per second. Each channel of a T1 line can be configured to carry either voice or data traffic.
E1 is similar to T1, except that E1 is the European format for digital transmission. E1 supports data rates at 2.048 Mbits per second. An E1 line comprises 32 channels at 64K bits per second each. Similar to T1, E1 can be configured to carry either voice or data traffic.
Prior to the present invention there has not been a telecommunication test system capable of running both T1 and E1 interfaces with a single set of voice channel resource cards. There are T1/E1 switchable test systems, however these systems included cards which had switchable framers and separate DSP resource cards. Previously, it was necessary to utilize a full set of T1 resource cards for testing T1 interfaces and a full set of E1 resource cards for testing E1 interfaces, all in a single system. One of the reasons for this is that T1 and E1 have different electrical interfaces so providing a solution would require a hardware based enhancement as the capability is not software programmable.
Alternatives to the present invention include duplicating the voice resources on both T1 and E1 Physical interface boards. This would result in using twice the number of boards or twice the number of systems to get the same number of channels. This method would prove to be costly to implement. Another alternative would involve modifying the system to use the physical interfaces without allocating full voice channel DSP resources. This method would provide a less flexible and capable test system. A further alternative would be to design a new board with a programmable part to accomplish the T1/E1 interface swapping. This method would be proprietary, slow, and expensive. Yet another alternative would be to physically swap boards in and out of the test system when needed. This method would also be expensive as well as prone to error, and would require manual labor by the customer. Still another alternative involves utilizing an external switch simulator that can convert T1 to E1 and vice versa. This method is expensive and impractical. In view of the above, it would be desirable to provide a multi-interface telephony test system using separate interface cards.